(a) Technical Field
The present invention relates to a power module, and more particularly, to a power module capable of increasing structural stability while remaining stable and reliable at high temperatures.
(b) Description of the Related Art
A power module is a component mounted in substantially all electronic devices and serves to supply power, convert power, and secure stability and efficiency.
Examples of the power module include: an insulated gate bipolar transistor (IGBT) module that may be placed in a dedicated case while having a plurality of diodes mounted therein, a current sensor-embedded intelligent power module (IPM) to which a protective circuit for overcurrent, overheat, or the like is added, and a metal oxide semiconductor field effect transistor (MOSFET) module.
In addition, some of power modules such as a dual side cooling type power module may be formed in a structure having two substrates spaced apart from each other to face each other.
The two substrates consist of an upper substrate and a lower substrate spaced apart from each other in up and down directions, in which a semiconductor element may be installed between the upper substrate and the lower substrate and a lead may be electrically connected to an electrode of the semiconductor element through a wire.
In this case, if the wire contacts the upper substrate, an electrical short-circuit may occur. For this reason, a spacer may be installed between the upper substrate and the lower substrate to secure a vertical interval between the upper substrate and the lower substrate, thereby preventing the wire from being contacted with the upper substrate.
However, the existing power module has a disadvantage in that if stress is applied to the semiconductor element due to thermal expansion under a high temperature condition, deformation of the spacer may be severe, and the deformation of the spacer may cause deformation of the upper substrate and/or the lower substrate, thus reducing stability and reliability of the power module at the high temperature.
Further, the spacer is mainly made of a Cu—Mo material. However, the spacer of the Cu—Mo material may have a large electric resistance and may be very expensive.
Further, the existing power module has a disadvantage in that both ends of the wire are bonded to the semiconductor element and the lead by ultrasonic bonding, and therefore short-circuiting at the bonding surface may easily occur due to a relatively lower external force. Moreover, a bonding area of the wire is narrow and therefore the wire may be easily fractured due to a concentrated external force.